1. Field of Invention
This invention relates to electron beam addressed liquid crystal cells and method of fabricating same.
2. Prior Art
Prior art electron beam addressed liquid crystal cells include configurations which utilize a thin substrate facing the electron beam source. As identified in U.S. Pat. No. 4,387,964 to Arrazola et al, Jun. 14, 1983, the thickness of the thin substrate facing the electron source influences trade offs involving resolution and mechanical stability. Consequently, it is imperative that a liquid crystal cell configuration which utilizes a thin substrate facing the electron beam source possess attributes which facilitates an optimal comprise.
The cell of U.S. Pat. No. 4,387,964 utilizes discrete spacers which are permanent to the cell in order to establish a separation gap in the liquid crystal cell. Several problems exist with the utilization of discrete spacers in liquid crystal cells. If a gasket is utilized on the peripheral of the cell, then tolerances associated the thickness of gaskets can introduce variations in cell to cell performance.
As identified in U.S. Pat. No. 4,784,883 to Chitwood et al, Nov. 15, 1988, alternative spacer techniques include the use of spheres distributed in the cell gap. Under high magnification, utilizing spacing spheres could adversely effect the quality of the optical image associated with the cell.
Alternative techniques to the use of a thin substrate include "charge transfer plates" and/or "wire mosaics". Such devices are well understood by those knowledgeable in the state of the art. Such devices are relatively complicated to fabricate. In addition, registration between the conductive pins and a serial scanning electron beam can pose additional problems.
Utilization of a target which incorporates a periodic structure with a serial scanned electron beam addressing mechanism would adversely effect one of the most desirable attributes associated with serial scanning element at a time electron beam scanning; the capability to conveniently change the format of the raster scan pattern. Applicant believes that use of any periodic structure in the target, for insuring a consistent cell gap and/or to transfer charge in the target, would tend to favor raster scan patterns which have a pixel count related to the spatial period of the periodic structure. Accordingly, a need exists for an electron beam addressed liquid crystal cell which overcomes the limitations of prior art.